The present invention relates to a refractory immersion spout or tube for use in discharging molten metal from a metallurgical vessel into a mold under the static pressure of the molten metal. This type of immersion tube includes a central inner axial passage through which the molten metal passes from the metallurgical vessel to the mold, with the lower end of the immersion tube being immersed within the molten metal as it fills the mold. The passage includes an upper inlet opening for receiving the molten metal from the metallurgical vessel, and at a lower outlet end of the immersion tube are provided one or a plurality of outlet openings which discharge the molten metal into the mold.
A disadvantage of this type of immersion tube is that the molten metal flowing through the immersion tube tends to swirl and be turbulent. This swirling and turbulent movement results in the formation of waves or oscillations in the molten metal within the mold. Such waves or oscillations result in nonuniformities at the surface of the solidified metal slab within the mold. Such nonuniformities lower the quality of the slab since uneven surfaces increase the amount of scrap. Furthermore, uneven surfaces lead to high tolerances in the thickness of the case slab.